JP3770036B2 - Toner for electrophotography and method for producing the same - Google Patents

Description

【００５８】
上記の実施例および比較例で得られたトナー100重量部にシリカ微粒子R972（日本アエロジル社製）1.2重量部をヘンシェルミキサ（三井金属鉱山社製）で30m/sの速度で３分間表面処理を行った。後述のキャリアとトナー混合比６重量％で混合して２成分非磁性現像剤を得、各現像剤を以下の評価項目について評価した。
【００５９】
（非オフセット温度域）
フルカラー複写機CF900（ミノルタ社製）の定着器を改造し、単独で定着温度を可変制御し通紙、定着できるようにした定着テスターを用いた。定着テスターにより複写した後、様々な定着温度で定着させ、ローラ１周後、オフセットしたトナー像がコピー用紙を汚しているかどうかを目視で評価し、汚染のない上限温度と下限温度を測定した。これらの温度幅が広いほど良好である。
【００６０】
（透光性）
上記定着テスターを用いて、非オフセット温度域の中心温度で定着させたOHP用紙上のコピー画像をオーバーヘッドプロジェクターEZ-2（富士写真フィルム社製）で目視評価した。
○：透明で色濁りなく良好であった；
×：不透明で実用上使用不可能であった。
【００６１】
結果を以下の表に示す。
【表２】

【００６２】
各現像剤を用いてCF900（ミノルタ社製）により１万枚複写し、初期と１万枚複写後の現像剤および複写画像について評価した。
（帯電量）
図１の電界分離方式の帯電量測定装置で、現像剤2gをスリーブ２上にまぶし、-2kvをバイアス電源４でスリーブ２に印加し、スリーブ２を1000rpm、１分間回転し、円筒電極１にトナー７を分離した。分離されたトナー重量（g）、トナー分離時に測定用コンデンサ５に流れ込んだ電荷量（μc）より、帯電量（μc/g）を計算した。
【００６３】
（画像濃度）
CF900（ミノルタ社製）による最大濃度のベタ複写画像における任意の10点の濃度をマクベス濃度計（マクベス社製）により測定し、これらの平均値ｘを求めて以下に従って評価した。
○：1.0＜ｘ＜1.3
△：0.8＜ｘ≦1.0または1.3≦ｘ＜1.5
×：ｘ≦0.8または1.5≦ｘ
【００６４】
（粒状性）
CF900（ミノルタ社製）による複写画像を目視により観察し、粒状性を以下のランク付けに従って評価した。なお、粒状性とは特に低濃度のベタ画像均一性（キメの良悪）をいう。
○：原稿と遜色なく良好であった；
△：原稿に比べ若干劣るが実用上問題なかった；
×：原稿に比べかなり劣り、実用上使用不可であった。
【００６５】
（地肌カブリ）
CF900（ミノルタ社製）による複写画像を目視により観察し、地肌カブリを以下のランク付けに従って評価した。なお、地肌カブリとは複写用紙上、本来の画像部以外に、低帯電・逆帯電のトナーが現像、転写されて発生するトナーによる汚れをいう。
○：カブリが見られず良好；
△：カブリがあるものの実用上問題なかった；
×：実用上使用不可であった。
【００６６】
結果を以下に示す。
【表３】

【００６７】
キャリア
ポリエステル樹脂バイロン200（東洋紡社製）をトルエン、イソプロパノールの混合溶媒に溶解し、平均径40μmの焼成フェライト粉F300（パウダーテック社製）にスピラコータ（岡田精工社製）で塗布、乾燥した。オーブン中140℃、２時間焼成後、解砕、フルイを行い、平均径42μmのポリエステル樹脂コートのフェライトキャリアを調製した。
【図面の簡単な説明】
【図１】 帯電量の測定に用いた帯電量測定装置の概略構成図を示す。
【符号の説明】
１：円筒電極、２：導電性スリーブ、３：磁性ロール、４：バイアス電極、５：測定用コンデンサ、６：現像剤、７：分離トナー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic toner.
[0002]
[Prior art]
In general, as a method of fixing a toner image on a recording paper in an image forming apparatus such as an electrophotographic copying machine or a printer, a heat pressing method using a heat roller or a belt member is often employed. Although this method is a relatively compact system, it has the advantages of high thermal efficiency and high-speed fixing. However, in this method, since the heat-melted toner contacts the heat roller at a high pressure, a part of the toner image on the recording paper adheres to the fixing member, and the toner image is defective, and adheres to the fixing member. The so-called offset phenomenon that the toner is transferred onto the recording paper at the time of the next fixing has been a problem. For this reason, a fluorine material or a silicone material having excellent surface releasability is used as the surface material of the fixing member, and further, a silicone oil having a good releasability is applied to the surface to prevent offset. However, the selection of the surface material alone is not sufficient to prevent offset, and the oil application method has problems such as excessive oil staining the recording paper or penetrating into the recording member and reducing the durability life. In addition, the installation of an oil supply / coating device has increased costs. Further, even if the offset can be prevented, the temperature range (non-offset temperature range) is narrow, and thus a problem arises in that the offset occurs again due to a change in the fixing temperature. In recent years, low-temperature fixing has been desired in order to increase the speed and energy saving of copying machines and printers, but the actual situation is that the offset has not produced sufficient results.
[0003]
Therefore, Japanese Patent Application Laid-Open No. 10-207116 has attempted to achieve oil-less fixing performance while maintaining the powder characteristics as a toner, using a toner that defines the amount of wax exposed on the surface and the average dispersed particle size of the wax. Has been made. In particular, the average dispersed particle size of the wax is 0.1 to 2 μm.
[0004]
[Problems to be solved by the invention]
However, since the above toner has a large average dispersed particle size of wax, and especially the maximum particle size is larger, when the obtained image is applied to an overhead projector (OHP), the image hardly transmits light and the OHP transmission There was a problem with light. In particular, when toner containing a large amount of wax capable of achieving oil-less fixing was used, the deterioration of OHP translucency was remarkable. In the toner, since the wax is positively exposed on the surface, the wax particles are easily removed from the toner, and the durability is remarkably lowered when continuously copied. That is, when continuous copying is performed using the above toner, toner fluidity is deteriorated and charging property is lowered, and image quality performance such as image density, graininess, and fog is remarkably lowered.
[0005]
The present invention has been made in view of the above circumstances, and provides a toner having a relatively wide fixing temperature range in which no offset occurs, excellent OHP translucency, excellent chargeability and image quality over a long period of time, and a method for producing the same. With the goal.
[0006]
[Means for Solving the Problems]
The present invention includes at least a binder resin, a colorant, and a release agent, and the release agent is dispersed in the particles with an average particle size of 0.1 μm or less and a maximum particle size of 0.4 μm or less. It relates to toner.
[0007]
The present invention also provides a liquid preparation step for preparing an oily phase obtained by dissolving and dispersing at least a binder resin or a polymerizable monomer, a colorant and a release agent in an organic solvent.
A granulation step of dispersing an oily phase in an aqueous phase to granulate droplet particles comprising the oily phase; and
A desolvation step of removing the organic solvent from the droplet particles or a polymerization-desolubility step of removing the organic solvent from the droplet particles while polymerizing a polymerizable monomer in the droplet particles;
The present invention relates to a method for producing an electrophotographic toner, wherein the liquid preparation step, the granulation step, and the desolubilization step or the polymerization-desolubility step are performed at a temperature equal to or higher than the temperature at which the release agent dissolves in the solvent.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The toner of the present invention contains at least a binder resin, a colorant, and a release agent, and the release agent has an average particle size of 0.1 μm or less, preferably 0.01 to 0.085 μm, and a maximum particle size of 0.4 μm or less, preferably in the particles. Is dispersed at 0.05 to 0.4 μm. In the toner of the present invention, since the release agent is finely dispersed in this way, even when the oilless fixing method is adopted, the low temperature offset is improved and the low temperature fixability is improved. The fixing temperature range in which no occurrence occurs is relatively wide. In addition, even when an opaque release agent is used, the transmission rate of visible light (wavelength of about 0.4 μm or more) increases, so that OHP translucency is improved and toner for color copiers and color printers. Suitable for use as Furthermore, since the release agent is finely dispersed in the toner particles and the release agent is prevented from falling off the toner, good chargeability and image quality can be maintained over a long period of time.
[0009]
When the average dispersed particle size of the release agent exceeds 0.1 μm or the maximum particle size exceeds 0.4 μm, offset is likely to occur, and the non-offset temperature range is narrowed. Further, when an image obtained using the toner is applied to an overhead projector (OHP), visible light hardly transmits through the image, and the OHP translucency becomes a problem. Furthermore, the release of the release agent from the toner becomes prominent, resulting in a problem in durability. That is, the chargeability is lowered by long-term use, and the image quality performance such as image density, graininess and fog is lowered. To do.
[0010]
The average dispersed particle size and maximum particle size of the release agent in the toner can be measured as follows. The dispersed particle size of the phase-separated release agent particles can be measured by solidifying the toner with a resin such as epoxy, slicing it to a thickness of about 1000 angstrom with a microtome, and observing with a transmission electron microscope. . In the present invention, the average dispersed particle size is determined from the dispersed particle size of any 50 release agent particles, and the maximum particle size is determined from any 100 release agent particles.
[0011]
The toner of the present invention may be produced by any method as long as the toner as described above can be obtained. However, by performing a series of steps at a temperature higher than the temperature at which the release agent dissolves in the solvent in a known wet method, the toner of the present invention can be obtained. Toner can be obtained effectively. That is, the toner of the present invention is
(I) a liquid preparation step for preparing an oily phase formed by dissolving and dispersing at least a binder resin or a polymerizable monomer, a colorant and a release agent in an organic solvent;
(II) a granulation step of dispersing the oily phase in the aqueous phase and granulating droplet particles comprising the oily phase; and
(III) a desolvation step of removing the organic solvent from the droplet particles, or (IV) a polymerization-desolubility step of removing the organic solvent from the droplet particles while polymerizing the polymerizable monomer in the droplet particles,
An electrophotography characterized in that the preparation step (I), the granulation step (II), and the desolubilization step (III) or the polymerization-desolubility step (IV) are carried out at a temperature above the temperature at which the release agent dissolves in the solvent The toner can be effectively obtained by the manufacturing method of the toner. In this way, in the wet method, by performing the above step at a temperature higher than the temperature at which the release agent dissolves in the solvent, that is, by performing the above step in a state in which the release agent is dissolved, In the desolubilization process, the release agent is precipitated. At the same time, the viscosity of the droplets increases due to the presence of the dissolved binder resin or the generated binder resin, so that the release agent grows to coarse particles. It is considered that finely dispersed toner can be obtained without aggregation. Even if the release agent is dissolved or finely dispersed in the solvent only in the liquid preparation step (I), the granulation step (II) and the desolubilization step (III) or the polymerization-desolubility step (IV) If the temperature of the release agent is lower than the temperature at which the release agent dissolves in the solvent, the release agent solubility in the solvent decreases, so the release agent that has been finely dispersed grows and aggregates, and the release agent that has been dissolved The agent precipitates, grows and aggregates, and the toner of the present invention cannot be obtained. In particular, when the temperature of the desolubilization process is low, the resin is still dissolved and the release agent abruptly recrystallizes in a state where the viscosity is low as the solvent evaporates.
Hereinafter, the case where the wet method is employed to obtain the toner of the present invention will be described in detail.
[0012]
The toner of the present invention can be obtained by any wet method including no polymerization process or a wet process including a polymerization process.
[0013]
When the toner of the present invention is produced using a wet method that does not include a polymerization process, for example, an emulsion dispersion granulation method,
(I) a liquid preparation step for preparing an oily phase formed by dissolving and dispersing at least a binder resin, a colorant, and a release agent in an organic solvent;
(II) a granulation step of dispersing the oily phase in the aqueous phase and granulating droplet particles comprising the oily phase; and
(III) When performing the desolubilization process to remove the organic solvent from the droplet particles,
The liquid preparation step (I), the granulation step (II), and the desolubilization step (III) can be obtained by performing at or above the temperature at which the release agent dissolves in the solvent.
[0014]
Specifically, first, an oily phase is prepared by dissolving and dispersing at least a binder resin, a colorant and a release agent in an organic solvent (preparation step (I)). In the present invention, the oily phase is prepared at a temperature equal to or higher than the temperature at which the release agent dissolves in the solvent (organic solvent), and the release agent is dissolved in the oily phase. When preparing the oil phase, it is only necessary to prepare an oil phase in which the release agent is dissolved as a result. For example, the toner component may be added to an organic solvent having a predetermined temperature, and mixed and stirred. Alternatively, the toner component may be added to an organic solvent at room temperature and mixed and stirred while heating to a predetermined temperature.
[0015]
The release agent that can be used in the present invention is not particularly limited as long as it can be dissolved in an organic solvent by heating, and known release agents in the field of toners, such as synthetic waxes, natural waxes and waxes, etc. Can be used. Among these release agents, from the viewpoint of improving offset resistance, it is preferable to use a release agent that dissolves in an organic solvent at a temperature of normal temperature to 90 ° C. Specifically, the concentration is 3.5% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more at a temperature of normal temperature to 90 ° C., preferably 25 to 60 ° C. with respect to the solvent used. It is preferable to use a release agent that dissolves in (release agent / (release agent + solvent)). Further, from the viewpoint of toner heat resistance and low-temperature fixability, the melting point is preferably 60 to 120 ° C.
[0016]
Specifically, as synthetic waxes, for example, synthetic hydrocarbon Fischer-Tropsch, polyethylene, polypropylene and other waxes, modified waxes such as montan, paraffin, microcrystalline, waxes such as esters, fatty acids, acid amides, ketones, etc. Is mentioned. Examples of natural waxes include plant-based carnauba, candelilla and rice waxes, jojoba oil, and the like. Other animal and mineral waxes can also be used. In particular, synthetic waxes such as esters, montans, and ketones, and natural waxes such as carnauba are suitable for the present invention in terms of melting point and solubility in organic solvents.
[0017]
The addition amount of the release agent is preferably 3 to 30 parts by weight, preferably 10 to 25 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint of heat resistance and stress resistance of the toner and charging performance. Conventionally, when an amount of wax that can achieve oil-less fixing is added, the OHP translucency deteriorates. However, in the present invention, such a problem does not occur even if a relatively large amount of wax is added as described above. Does not occur.
[0018]
The organic solvent that can be used in the present invention is not particularly limited as long as it is a known organic solvent that can dissolve the release agent. For example, aromatic solvents such as toluene and xylene, and ester solvents such as ethyl acetate and butyl acetate. Ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as isopropyl alcohol, n-butanol and ethanol, and halogen solvents such as chloroform and carbon tetrachloride. These organic solvents may be used alone or in admixture of two or more. These solvents are used in a proportion of 50 to 95% by weight in the oily phase as long as they do not adversely affect granulation in the granulation step described later.
[0019]
When using ester wax or carnauba wax as the mold release agent, it is preferable to use toluene as the organic solvent.
[0020]
The temperature at which the oily phase is prepared is not particularly limited as long as the release agent can be dissolved in the organic solvent, and is appropriately selected depending on the type of the release agent and the organic solvent used. Even if the temperature is set too high, it is not preferable from the viewpoint of production efficiency. Therefore, the temperature is usually set within a range of normal temperature to 90 ° C., preferably 25 to 80 ° C. For example, when ester wax or carnauba wax is used as the release agent and toluene is used as the organic solvent, the temperature is preferably 35 to 70 ° C, and preferably 40 to 60 ° C.
[0021]
As the binder resin, resins that can be dissolved in the organic solvent can be used. For example, polyester resins, styrene resins, (meth) acrylic resins, styrene- (meth) acrylic copolymer resins, olefins. It is possible to use one kind or two or more kinds of known various resins such as resin, polyamide resin, polycarbonate resin, polyether resin, polyvinyl acetate resin, polysulfone resin, epoxy resin and polyurethane resin. is there. In the present invention, it is preferable to use a polyester resin from the viewpoint of further fine dispersion of the release agent, solubility in a solvent, toner fixing performance, translucency, and heat resistance. It is more preferable to use a polyester resin having a molecular weight (Mn) of 2000 to 8000, a weight average molecular weight / number average molecular weight (Mw / Mn) of 5 to 20, and a glass transition point of 55 to 70 ° C. Such polyester resins are easily dissolved by the above organic solvents, and even when a release agent is added, the OHP translucency is more effectively maintained, while the low-temperature and high-temperature offset resistance and the fixing performance are effectively improved. It is to do. Further, the heat resistance and stress resistance necessary for the toner are also effectively maintained.
[0022]
In the present invention, when ester wax or carnauba wax is used as a release agent, it is preferable to use a polyester resin as a binder resin. This is because the compatibility between the release agent and the binder resin is good, so that fine dispersion of the release agent is achieved more effectively, and the translucency is further improved because the refractive index of the resin and the wax is close.
[0023]
The colorant is not particularly limited, and a known pigment / dye conventionally used as a colorant for toner can be used.
Examples of the black pigment include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite.
Examples of the yellow pigment include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, and benzidine yellow G.
Examples of orange pigments include red chrome yellow, molybdenum orange, permanent orange GTR, parazolone orange, and vulcan orange.
Examples of red pigments include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watch red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. is there.
[0024]
Examples of blue pigments include bitumen, cobalt blue, alkali blue lake, victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, and phthalocyanine blue.
Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white.
These colorants can be used alone or in combination of two or more. Usually, it is desirable to use 1 to 20 parts by weight, preferably 2 to 15 parts by weight with respect to 100 parts by weight of the binder resin.
[0025]
A charge control agent may be dissolved or finely dispersed in the oily phase. Any charge control agent (CCA) can be used as long as it can be dissolved or finely dispersed in the organic solvent. Examples of negative charge control agents include metal-containing complex salt Bontron E81, E84 (manufactured by Orient Chemical Co., Ltd.), LR147 (manufactured by Nippon Carlit), thioindigo pigment, calixarene compound Bontron E89 (manufactured by Orient Chemical Co., Ltd.), fluorine-containing compound Compound copy charge NX VP434 (made by Hoechst), FT-310 (made by Neos), etc. are mentioned. Examples of the positive charge control agent include quaternary ammonium salt P-51 (manufactured by Orient Chemical Co.), copy charge PX VP435 (manufactured by Hoechst), and the like. For a color toner, a material which can give positive or negative charge by a triboelectric charge from a transparent color without impairing the color tone is preferable. One or more of these may be used. The addition amount of the charge control agent is not particularly limited, but is 0.1 to 4 parts by weight, preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the binder resin.
[0026]
Next, the obtained oily phase is dispersed in the aqueous phase to granulate droplet particles composed of the oily phase (granulation step (II)). That is, a dispersion system (O / W emulsion) in which liquid particles comprising an oily phase are dispersed in an aqueous phase is prepared. In the present invention, granulation is performed at a temperature at which the release agent dissolved in the droplets does not precipitate, that is, at a temperature higher than the temperature at which the release agent dissolves in the solvent (organic solvent). Usually, granulation is performed while maintaining the temperature of the liquid preparation process. Therefore, at the time of dispersion, it is preferable that the oily phase and the aqueous phase are respectively controlled at a predetermined temperature, and then mixed, dispersed and granulated.
[0027]
In granulation, the oily phase may be added to the aqueous phase and emulsified, and the oily phase may be dispersed in the aqueous phase, or the aqueous phase may be added to the oily phase and phase-inverted and emulsified to make the oily phase aqueous. It may be dispersed in the phase.
[0028]
The aqueous phase is formed by adding an additive such as a dispersant and / or a dispersion aid to water as required. The dispersant is preferably a hydrophilic colloid in the aqueous phase, particularly gelatin, gum arabic, agar, cellulose derivatives, synthetic polymers (eg, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylate, polymethacrylate, etc.). Insoluble inorganic salts (for example, calcium phosphate), hydrophilic silica and the like. A surfactant is usually used as a dispersion aid, a natural surfactant such as aponin, a nonionic surfactant such as alkylene oxide, glycerin or glycidol, carboxylic acid, sulfonic acid, phosphoric acid, sulfate ester group, Examples include anionic surfactants containing acidic groups such as phosphate ester groups.
[0029]
The concentration of the dispersant and the dispersion aid in the aqueous phase is not particularly limited, and generally 1 to 10% by weight and 0.001 to 1% by weight are preferable, respectively.
[0030]
When dispersing the oily phase in the aqueous phase, it is preferable to control the diameter of the liquid particles in the oily phase by stirring so that the toner particles obtained have a desired particle size. The mixing volume ratio of the oily phase to the aqueous phase (oily phase / aqueous phase) can be selected between 1/1 to 1/4 in consideration of the emulsion stability.
[0031]
After granulating the droplet particles composed of the oil phase, the organic solvent is removed from the droplet particles (demelting step (III)). Desolubilization may be performed at a temperature at which the release agent does not precipitate due to a decrease in the solubility of the release agent in the organic solvent as the temperature in the system decreases. Usually, the release agent is a solvent (organic solvent). It is carried out over a long time while maintaining the temperature of the preparation step. In this way, by performing the desorption while avoiding the precipitation of the release agent due to a decrease in system temperature (decrease in solubility), only the release agent is precipitated due to solvent removal, and at the same time, the dissolution in the droplet particles Therefore, it is considered that the release agent fine particles precipitated in the toner can be finely dispersed without growing or agglomerating.
[0032]
In the present invention, it is preferable to perform the demelting step over a long time. This is because the release agent can be finely dispersed more effectively. Since it differs with each kind of organic solvent, mold release agent, and resin, it cannot be limited.
[0033]
After the removal of the organic solvent is completed, the toner of the present invention can be obtained by cooling, repeating filtration / washing several times, drying and crushing.
[0034]
The toner of the present invention can also be obtained by employing a wet method including a polymerization process, such as a suspension polymerization method, an emulsion polymerization method, an emulsion polymerization aggregation method, a seed polymerization method, and an interfacial polymerization method. Hereinafter, the case where the toner of the present invention is obtained by adopting a wet method including a polymerization process will be described. However, unless otherwise specified, the same process as in the case of employing the wet method not including the polymerization process is used. In the wet process including a polymerization process, the polymerizable monomer also acts as a “solvent”, and therefore “solvent” means “a mixed solvent of an organic solvent and a polymerizable monomer”. Further, regarding the addition amount, “100 parts by weight of the binder resin” is read as “100 parts by weight of the polymerizable monomer”.
[0035]
When the toner of the present invention is produced using a wet method including a polymerization process, particularly a suspension polymerization method,
(I) a liquid preparation step for preparing an oily phase obtained by dissolving / dispersing at least a polymerizable monomer, a colorant and a release agent in an organic solvent;
(II) a granulation step of dispersing the oily phase in the aqueous phase and granulating droplet particles comprising the oily phase; and
(IV) In performing the polymerization-desolubilization step of removing the organic solvent from the droplet particles while polymerizing the polymerizable monomer in the droplet particles,
The liquid preparation step (I), the granulation step (II), and the polymerization-desolubilization step (IV) can be obtained by performing at or above the temperature at which the release agent dissolves in the solvent.
[0036]
Specifically, first, an oily phase is prepared by dissolving and dispersing at least a polymerizable monomer, a colorant, and a release agent in an organic solvent (preparation step (I)). In the wet method including a polymerization process, the oily phase is prepared at a temperature higher than the temperature at which the release agent dissolves in the solvent, that is, the mixed solvent of the organic solvent and the polymerizable monomer, and the release agent is dissolved in the oily phase. Yes.
[0037]
The organic solvent is usually used at a ratio of 5% by weight or more in the oily phase, but may not be used. When no organic solvent is used, the oily phase is prepared above the temperature at which the release agent dissolves in the polymerizable monomer.
[0038]
The polymerizable monomer is not particularly limited as long as it can constitute the binder resin and has hydrophobicity. For example, styrene resin, (meth) acrylic resin, styrene- (meth) acrylic copolymer Examples thereof include vinyl monomers that are raw materials for resins and the like.
[0039]
It is preferable that a polymerization initiator is added to the oily phase. As a polymerization initiator, radical polymerization initiators, such as an azo compound type, a hydroperoxide type, and a redox type, are mentioned, for example.
[0040]
Next, the obtained oily phase is dispersed in the aqueous phase to granulate droplet particles composed of the oily phase (granulation step (II)). In the present invention, granulation is performed at a temperature at which the release agent dissolved in the droplets does not precipitate, that is, the temperature at which the release agent is dissolved in a solvent (a mixed solvent of an organic solvent and a polymerizable monomer). This is done. Usually, granulation is performed while maintaining the temperature of the liquid preparation process. In the case where no organic solvent is used, the granulation is performed at a temperature higher than the temperature at which the release agent dissolves in the polymerizable monomer.
[0041]
Next, the organic solvent is removed from the droplet particles while polymerizing the polymerizable monomer in the droplet particles (polymerization-desolubilization step (IV)). That is, in this process, desorption is performed while polymerization is performed, and as a result, the desorption is completed at the end of the polymerization.
[0042]
Polymerization-desolubilization is performed at a temperature at which the release agent does not precipitate due to a decrease in release agent solubility accompanying a decrease in system temperature, that is, the release agent is a solvent (organic solvent and polymerizable monomer). At a temperature equal to or higher than the temperature at which the solvent is dissolved. In the case where no organic solvent is used, the polymerization / dissolution is performed at a temperature equal to or higher than the temperature at which the release agent is dissolved in the polymerizable monomer. In this way, by performing polymerization-desolubility while avoiding precipitation of the release agent due to a decrease in system temperature (decrease in solubility), only removal of the solvent and precipitation of the release agent due to resin formation occur at the same time. It is considered that the release agent fine particles deposited in the toner can be finely dispersed without growing or aggregating because the viscosity is increased by removing the solvent and generating the resin in the droplet particles.
[0043]
Specifically, the conditions such as the temperature and time of the polymerization-demelting step are not particularly limited as long as the above requirements are satisfied with respect to the temperature, but have the Mn, Mw / Mn and glass transition point described in the description of the binder resin. It is preferable that the conditions are such that a resin is obtained.
[0044]
In the present invention, it is preferable to perform the polymerization-desolubilization process over a long period of time. This is because the release agent can be finely dispersed more effectively.
[0045]
After the removal of the organic solvent is completed, the toner of the present invention can be obtained by cooling, repeating filtration / washing several times, drying and crushing.
[0046]
The toner of the present invention that can be produced by the above production method is desirably controlled to have a volume average particle diameter of 3 to 10 μm, preferably 4 to 8 μm.
[0047]
The toner of the present invention is preferably surface-treated with fine particles from the viewpoint of improving fluidity, chargeability, heat resistance and the like. As the fine particle material, conventionally known fine particle materials externally added to toner in the field of electrophotography can be used, and examples thereof include metal oxides, intermetallic compounds, and resins. Specific examples of the metal oxide include silica, titanium oxide, alumina, and zirconia. Examples of the intermetallic compound include strontium titanate, silicon carbide, silicon nitride, and the like. Examples of the resin include a polymer fluoride, a silicone compound, an acrylic resin, and the like. The addition amount of the fine particles is suitably 0.2 to 3 parts by weight with respect to 100 parts by weight of the toner.
[0048]
Since the toner of the present invention can contain a relatively large amount of a release agent in a finely dispersed state, the object of the present invention can be effectively achieved even when used in a copying machine employing an oilless fixing method.
[0049]
The toner of the present invention can be used as a two-component developing toner used with a carrier or as a one-component developing toner not using a carrier.
[0050]
As the carrier used with the toner of the present invention, a known carrier can be used. For example, a carrier made of magnetic particles such as iron powder and ferrite, and a coated carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin. Alternatively, any of a dispersion type carrier in which a magnetic fine powder is dispersed in a binder resin can be used.
Hereinafter, the present invention will be described in more detail with reference to examples.
[0051]
【Example】
Example 1
Number average molecular weight Mn is 2,800, weight average molecular weight / number average molecular weight (Mw / Mn) is 7, and Tg is 68 ° C. ) Put together with 0.5g in a 2 liter plastic bottle, mix and disperse with Ultra Turrax (IKA) for 30 minutes, then add 20g of ester wax HOE-WAX F (Clariant) with a melting point of 80 ° C to 50 ° C Then, an oily phase in which wax was dissolved in toluene was prepared by heating. Next, 11 g of sodium alkyldiphenyl ether disulfonate is added to 1100 g of a 3.5 wt% aqueous solution of sodium polyacrylate to prepare an aqueous phase at 50 ° C., and this is mixed in an oily phase maintained at 50 ° C. Was kept at 50 ° C. and emulsified by stirring at 3500 rpm for 10 minutes with a TK auto homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). Immediately, the mixture was stirred for 20 hours with a three-one motor in a thermostatic bath at 50 to 55 ° C. to remove toluene, and after cooling, filtration / washing was repeated several times. The washed toner cake is transferred to a stainless steel vat, dried at 35 ° C for 48 hours in a constant temperature dryer, crushed using a ball mill, and sieved with a 90 µm mesh to obtain a toner with an average particle size of 6.2 µm. It was. As a result of observation with a transmission electron microscope (50,000 times) (hereinafter the same), wax particles having an average particle diameter of 0.05 μm and a maximum particle diameter of 0.23 μm were dispersed inside the toner particles.
[0052]
(Example 2)
A toner having an average particle size of 7.5 μm was obtained in the same manner as in Example 1 except that 10 g of Carnauba 45T-1 (manufactured by Seiro Co., Ltd.) having a melting point of 93 ° C. was used as the wax. Wax particles having an average particle size of 0.08 μm and a maximum particle size of 0.37 μm were dispersed inside the toner particles.
[0053]
Example 3
A toner having an average particle size of 5.4 μm was obtained in the same manner as in Example 1 except that polyester having Mn of 3000, Mw / Mn of 9 and glass transition point of 60 ° C. was used as the binder resin. Wax particles having an average particle size of 0.04 μm and a maximum particle size of 0.18 μm were dispersed inside the toner particles.
[0054]
(Comparative Example 1)
A toner having an average particle size of 7.0 μm was obtained in the same manner as in Example 1 except that 20 g of n-hexadecyl ether having a melting point of 55 ° C. was used as the wax. Wax particles having an average particle size of 1.5 μm and a maximum particle size of 4.8 μm were dispersed inside the toner particles.
[0055]
(Comparative Example 2)
A toner having an average particle size of 8.6 μm was obtained in the same manner as in Example 1 except that 2 g of polyethylene wax 400P (manufactured by Mitsui Chemicals) having a melting point of 126 ° C. was used as the wax. Wax particles having an average particle size of 3.5 μm and a maximum particle size of 6.2 μm were dispersed inside the toner particles.
[0056]
Table 1 summarizes the type, melting point, addition amount and concentration of the wax used in each example and comparative example, and the saturated concentration of each wax with respect to toluene at each temperature.
[0057]
[Table 1]

[0058]
100 parts by weight of the toner obtained in the above Examples and Comparative Examples was subjected to surface treatment for 3 minutes at a speed of 30 m / s with 1.2 parts by weight of silica fine particles R972 (manufactured by Nippon Aerosil Co., Ltd.) using a Henschel mixer (manufactured by Mitsui Metal Mining). went. A two-component nonmagnetic developer was obtained by mixing with a carrier described later at a toner mixing ratio of 6% by weight, and each developer was evaluated for the following evaluation items.
[0059]
(Non-offset temperature range)
A fixing tester that modifies the fixing device of the full-color copier CF900 (manufactured by Minolta Co., Ltd.) and variably controls the fixing temperature to enable paper passing and fixing is used. After copying with a fixing tester, fixing was performed at various fixing temperatures. After one rotation of the roller, it was visually evaluated whether the offset toner image stained the copy paper, and the upper and lower temperatures without contamination were measured. The wider these temperature ranges, the better.
[0060]
(Translucent)
Using the fixing tester, a copy image on OHP paper fixed at the center temperature in the non-offset temperature range was visually evaluated with an overhead projector EZ-2 (Fuji Photo Film Co., Ltd.).
○: Transparent and good without turbidity;
X: Opaque and practically unusable.
[0061]
The results are shown in the table below.
[Table 2]

[0062]
Using each developer, 10,000 copies were made with CF900 (Minolta Co., Ltd.), and the developer and copied images after the initial and 10,000 copies were evaluated.
(Charge amount)
In the electric field separation type charge amount measuring apparatus shown in FIG. 1, 2 g of developer is coated on the sleeve 2, −2 kv is applied to the sleeve 2 by the bias power source 4, the sleeve 2 is rotated at 1000 rpm for 1 minute, and the cylindrical electrode 1 is applied. Toner 7 was separated. The charge amount (μc / g) was calculated from the separated toner weight (g) and the charge amount (μc) flowing into the measuring capacitor 5 during toner separation.
[0063]
(Image density)
The density of any 10 points in the solid copy image with the maximum density by CF900 (manufactured by Minolta) was measured with a Macbeth densitometer (manufactured by Macbeth), and the average value x was obtained and evaluated according to the following.
○: 1.0 <x <1.3
Δ: 0.8 <x ≦ 1.0 or 1.3 ≦ x <1.5
X: x ≦ 0.8 or 1.5 ≦ x
[0064]
(Granularity)
A copy image by CF900 (manufactured by Minolta) was visually observed, and the graininess was evaluated according to the following ranking. Note that the granularity means the uniformity of a solid image with a low density (quality of texture).
○: It was good without being inferior to the original
Δ: Slightly inferior to the original, but no problem in practical use;
X: It was considerably inferior to the original and could not be used practically.
[0065]
(Skin fog)
Copy images by CF900 (Minolta) were visually observed, and background fog was evaluated according to the following ranking. The background fogging refers to a stain caused by toner generated by developing and transferring low-charge / reverse-charge toner on a copy sheet in addition to the original image portion.
○: Good without fogging;
Δ: Although there was fog, there was no problem in practical use;
X: Unusable for practical use.
[0066]
The results are shown below.
[Table 3]

[0067]
Career
Polyester resin Byron 200 (manufactured by Toyobo Co., Ltd.) was dissolved in a mixed solvent of toluene and isopropanol, applied to a sintered ferrite powder F300 (manufactured by Powder Tech Co.) having an average diameter of 40 μm with a Spiracoater (manufactured by Okada Seiko Co., Ltd.) and dried. After firing in an oven at 140 ° C. for 2 hours, crushing and sieving were carried out to prepare a polyester resin-coated ferrite carrier having an average diameter of 42 μm.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a charge amount measuring apparatus used for measuring a charge amount.
[Explanation of symbols]
1: cylindrical electrode, 2: conductive sleeve, 3: magnetic roll, 4: bias electrode, 5: capacitor for measurement, 6: developer, 7: separated toner.

Claims (1)

  A liquid preparation step for preparing an oily phase formed by dissolving and dispersing at least a binder resin, a colorant and a release agent in an organic solvent, and granulating droplet particles comprising the oily phase by dispersing the oily phase in the aqueous phase A degreasing step for removing the organic solvent from the droplet particles, and performing the liquid preparation step, the granulating step, and the demelting step at a temperature equal to or higher than the temperature at which the release agent dissolves in the solvent. Production of an electrophotographic toner comprising at least a binder resin, a colorant and a release agent, wherein the release agent is dispersed in the particles with an average particle size of 0.1 μm or less and a maximum particle size of 0.4 μm or less. Method.

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